The electronics are based upon the open-source Arduino prototyping platform [36], which exposes
the digital and analog I/O as well as processing capabilities of an Atmel Atmega microprocessor in a
single convenient package. The platform encapsulates the hardware required to interface the Arduino
with a host computer and includes a custom bootloader that executes compiled C++ code that can be
developed in the Arduino integrated development environment (IDE). The platform is designed to use
“shields” or customized electronic boards that can bepressed into place and that typically come with
software libraries so as to facilitate integration ofboard features into the custom code developed by the
end user. A display shield incorporating a 16 × 2 character alphanumeric LCD and D-pad button
interface was used to navigate and select device functions and display the results of analysis. The
shield is also open source, supplied by Adafruit Industries [37], a company dedicated to developing
and providing low-cost, innovative and useful open-source electronic solutions. A single 5 mm